In response to CDC-RFA-DD06-001 (Developing Methodologies to Determine the Prevalence of Autism Spectrum Disorders in Early Childhood...Populations), we propose a California Monitoring of Early Childhood Autism (CA-MECA) project under the leadership of the California Department of Health Services (DHS) and in partnership with Kaiser Permanente of Northern California (KPNC)and multiple health and education providers in Santa Clara County, California, a large, multi-cultural community with almost 100,000 children <4 years of age. The goal of this 12-month project is to develop a plan for a multi-source population-based Autism Spectrum Disorders (ASD) surveillance system for children <4 years of age and increase public awareness and participation in ASD early recognition efforts. With the help of local Regional Centers for the Developmentally Disabled, the local public health department, special education department, medical providers, day care providers, and parent support groups, CA-MECA will 1) identify sources and data linkages for ascertainment of children <4 years of age with ASD or who are considered "at risk" of ASD; 2) determine the best methods needed for prevalence estimates; 3) assess the feasibility of establishing this system, completeness of ascertainment, validity of Dx, and determine the necessary resources needed for full implementation; and 4) assess current early screening efforts, diagnostic practices and referral patterns and develop strategies to enhance ASD screening and diagnosis services and ASD awareness in the county. [unreadable] Data from the CA-MECA project may be valuable in a variety of capacities including tracking changes in [unreadable] ASD occurrence over time, identifying ASD risk factors, planning and delivery of ASD related services, [unreadable] identifying underserved subgroups in the population, and improving early screening and diagnostic practices. [unreadable] [unreadable] [unreadable] [unreadable]